1. Technical Field
The present invention relates generally to abrasive jet systems and, in particular, to abrasive jet systems having a vented cutting head body.
2. Description of the Related Art
Conventional abrasive jet systems are used to process workpieces by pressurizing fluid and then delivering the pressurized fluid against a workpiece. Abrasive jet systems produce high-pressure abrasive fluid jets (commonly referred to as abrasive jets) suitable for cutting through hard materials. High-pressure fluid can flow through a jet-forming jewel orifice of a cutting head assembly to form a high-pressure fluid jet into which abrasive particles are entrained. The high-pressure abrasive fluid jet is discharged from the cutting head assembly towards the workpiece.
The abrasive and the fluid jet are often mixed together in a mixing chamber within the cutting head assembly. Abrasive delivered into the mixing chamber has a tendency to move upstream through the cutting head assembly towards the jewel orifice. This is because the upstream pressure (e.g., the pressure in a flow passageway between the mixing chamber and the jewel orifice) may be lower than the pressure in the mixing chamber. The pressure differential often leads to abrasive movement that may result in the abrasive striking and causing damage to a jewel orifice holder supporting the jewel orifice.
The abrasive may also eventually migrate upstream past the jewel orifice holder and ultimately to the top of the jewel orifice. Abrasive may slowly accumulate on the upstream surfaces of the jewel orifice. If some of the accumulated abrasive becomes dislodged, it may be picked-up by the high-pressure fluid that is forced through the jet-forming jewel orifice. The picked-up abrasive may quickly damage the jewel orifice, resulting in malfunctioning and/or significantly impaired performance of the cutting head assembly. The abrasive jet system has to be shut down to replace the damaged jewel orifice and clean abrasive from the cutting head assembly such that the waterjet cutting process can be performed once again. Unfortunately, the downtime may significantly reduce the productivity of the abrasive jet system.